Pulley-block



(N0 ModeL) T. BARBER.

PULLEY BLOCK.

INVENTOR.

'vzazw' By K) M 1, Zn; ATTORNEYS N. PETERS, Pholwljihngnphnr. Walhmgtcn. D. c.

NITE STATES 1 ATENT Fries.

THOMAS BARBER, OF FLA'IBUSH, NEW YORK.

PULLEY-BLOCK.

SESPECIFICA'I'ION forming part of Letters Patent No 320,206, dated June 16, 1885.

Application lilvd March 27, 1885.

To all whom it may concern.-

Be it known that I, THOMAS BARBER, a citizen of the United States, residing at Flatbush, in the county of Kings and State ofNew York, have invented new and useful Improvements in Pulley-Blocks, of which the following is a specification.

This invention relates to improvements in hoisting apparatus; and it consists in the combination,inapulley-block,oftwoworm-wheels, a worm adapted to engage the worm-wheels, sheaves which rotatewiththeworm-wheels,and an endless chain extending round the sheaves; and, furthermore, it consists in the combination, in a differential pulley-block, of two worm-wheels of different diameter, a worm provided with right and left hand threads and adapted to engage the said worm wheels, sheaves which rotate with the worm-wheels, and an endless chain extending round the sheaves. In order that the chain which extends round the sheaves and which carries the load may be quickly lowered, means are also provided for throwing the upper worm-gear clear of the worm, so that the upper sheave may rotate with its worm-wheel independently of said worm, while the lower sheave remains stationary.

In the accompanying drawings, Figure 1 represents a vertical section in the plane y y, Fig. 2, of my improved worm-wheel block. Fig. 2 is a Vertical section in' the plane 3 3/, Fig. 1.

Similar letters indicate corresponding parts.

In the drawings, the letter A designates the frame of my hoisting apparatus, which is sus pended by means of a swiveling book, a, in the usual manner. B is the upper worm-wheel, which is mounted on a pintle, O, and is provided with a shoulder, b, on which is mounted the upper sheave, D, which has formed thereon a shoulder, d, for apurpose which will be here inafter described. The worm-wheel B and the upper sheave, D, are keyed to each other, so that they will rotate together, but are not secured to the pintle in order that the same will remain stationary. B is the lower wormwheel, which is mounted on a pintle, O, and

has formed thereon two shoulders, on one of I which is mounted and keyed the lower sheave, D. Between the upper and lower wormwheels, B B, is situated a worm, E, which has (No model.)

suitable hearings in crosspieces 0 of the frame, and which has cut thereon right and left hand threads, and, as shown in the drawings, the right-h and thread engages with the upper and the left-hand thread engages with the lower worm-wheel. Motion is given to this worm by a pulley, E, or hand-wheel, or by a chain in the ordinary manner, or by any other means.

The pintle O,carrying the upper sheave and worm-wheel, has its bearings in the slots f f, formed in the sides of the frame A, and can therefore be moved upward, so as to clear the worm-wheel from the worm. This changing of the position of the pintle is effected by means of a loose collar, F, which surrounds the shoulder d on the upper sheave, D, and is connected by means of the hook g, secured thereto to the rope h, which runs over a pulley, i, mounted on the upper end of the frame A, and by drawing down on this rope it is evident that the pintle will be lifted out of its bearing and the chain G can be quickly lowered. The upper and lower sheaves are connected by means of this endless chain G to a running pulley, H, of the usual construction,and said sheaves may be provided with spurs or projections on their faces, which engage with the chain as in the ordinary chain-pulley, or, as shown in the drawings, may be provided with circumferential grooves, into which the chain partly sinks.

In the example shown in the drawings, the upper worm-gear, B, is of a larger diameter than the lower worm-gear, B, from,which it is evident that the upper sheave, D, will rotate slower than the lower sheave, D, provided that the threads on the worm have the same pitch, and consequently since the pulleys will rotate in the same direction and the chain from the running pulley H passes over the front of the sheave D and behind the sheave D the block will act differentially. It is also evident that the pitches of the threads on the worm can be made to vary from each other-that is to say, the pitch of one can be made any multiple of the other and the gears be of the same diameter, whereby the same result will be obtained as before. The differences of the speed between the two sheaves will depend on the power required from the block, and for heavy work the worm is best made double or triple threaded.

Instead of having the sheaves of the same diameter, they can be made to differ, as in the ordinary differential block, and the worm-gears can be made of the same diameter, or the difference between the diameters can be made correspondingly smaller.

What I claim as new, and desire to secure by Letters Patent, is

1. In a pulley-block, the combination of two worm-Wheels, a worm adapted to engage the worm-wheels, the sheaves rotating with'the said worm-wheels, and an endless chain extending round the sheaves, substantially as shown and described.

2. In a'pulley-block, the combination of two worm-wheels, a worm having right and left hand threads and adapted to engage the wormwheels, the sheaves rotating with the said worm-wheels, and an endless chain extending round the sheaves, substantially as shown and described.

3. In apulley-bloek, the combination of two Worm-wheels of different diameter, a worm having right and left hand threads adapted to engage the worm-wheels, the sheaves rotating with said worm-wheels, and an endless chain extending round the sheaves, substantially as shown and described.

4. In a pulley-block, the combination of two worm-wheels, a worm adapted to engage the worm-wheels, the sheaves rotating with the said worm-wheels, an endless chain extending round the sheaves, the collar surrounding the upper pintle, and a rope attached thereto for raising the pintle from its bearings, substantially as and for the purpose described.

In testimony whereof I have hereunto set my hand and seal'in the presence of two subscribing witnesses.

THOMAS BARBER. [L. s.]

Witnesses:

W. HAUFF, E. F. KAsTENJaUBER. 

